Lock stitch sewing machine



March 21, 1961 o. F. HOPPE 2,975,738

LOCK STITCH SEWING MACHINE Filed May 17, 1957 2 Sheets-Sheet 1 Inven forO zto F Hoppe March 21, 1961 HQPPE 2,975,738

LOCK STITCH SEWING MACHINE Filed May l7, 1957 2 Sheets-Sheet 2 Inventor4 I Otfo F. HOPPG 7 LOCK STITCH SEWING MACHINE Otto F. Hoppe, Schonberg(Taunus), Germany, assignor,

by mesne assignments, to United Shoe Machinery Corporation, Boston,Mass, a corporation of New Jersey Filed May 17, 1957, Ser. No. 659,787

Claims priority, application Germany June 1, 1956 5 Claims. (Cl. 112-233This invention relates tolockstitch shoe outsole sewing machines of thehook needle type having an improved form of shuttle for preventingentanglement of locking thread within a supply retainer and is herewithillustrated as embodied in a locking thread supply retainer for a sewingmachine of the type disclosed in United States Letters Patent No.2,056,670, granted October-6, 1936, in the names of Gouldbourn et al.

The machine ofthe patent above referred to is particularly intended foruse in sewing outsoles to shoes of the Goodyear welt type and theshuttle of that machine has rotatably mounted within it a locking threadsupply retainer or case carrying a flanged bobbin with a quantity ofthread wound between its flanges. The thread'case in that'machine isheld stationary and the shuttle rotates continuously to carry each loopof needle thread about the locking thread supply case. It has beenproposed to employ in that machine a locking thread manufactured withfibers having a certain number of twists per inch of thread and then toutilize a shuttle having an integral thread supply retainer or case, orat least one which is not mounted for rotation in the shuttle, so thatthe rotation of the shuttle modifies the number of twists per inch asthe thread is withdrawn from the thread retainer or case into the work.In this way, a highly twisted thread may be provided on the supplybobbin and as the shuttle with the retainer case rotatessome of thetwists in the thread are removed, sothat the thread becomes much softerand more readily conformedto the configuration required, according to.desirable sewing practices. In modifying the twist in this way it hasbeen found that difficulty oftenis encountered from a tendency for thethread tobecome entangled within the thread retainer case r asthe'result of use of high twist thread when a modifying twist works itsway from the work back into loose accumulations within the thread case.To avoid this difliculty the usual form of frictional thread tensiondevice is ineifective, the irregular withdrawal of thread common withsewing operations causing the supply bobbin to overrun excessively andto. create large accumulations of loose easily entangled thread withinthe locking thread retainer case.

It is, an object of the invention to prevent :overrunning of a bobbin ina locking thread supply' case or other retainer for a lockstitch shoesewing machine of the type referred to, andmore particularly to preventaccumulations and consequent entanglementof hard twisted threadcontained ona. supply bobbin when the thread retainer for supporting thebobbin rotates with the shuttle in a manner to modify the twist in thethread, the means for preventing overrunning in the bobbin also servingto concentrate the modification of the twist in the thread outside thethread case between it and the work.

As illustrated in the accompanying drawings, the means for preventingoverrunning of the bobbin and working back of the modifying twist in thethread into the thread supplycase or retainer comprises athread-engaging member yieldingly mounted on the thread supply retainerinite States Patent C) 2,975,138 Patented Mar. 21,1961

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dependently of the bobbin between which thread-engaging member and thebobbin the thread is frictionally pressed. By such construction rotationof the bobbin in the supply retainer is controlled by direct frictionalengagement of the bobbinwith the thread, the thread movement furnishinga fresh, fibrous frictional surface for stopping the bobbin rotationafter each length of thread is withdrawn therefrom.

Preferably, the pressure member is in the form of an arm pivoted on thelocking thread supply retainer and is provided with a friction surfaceto force the thread against a flange of the bobbin. In one form of thepressure member its initial force is exerted by a yielding membermounted on the supply retainer and to reduce the force of the yieldingmember in proportion to the tension on the thread exerted during itswithdrawal a guide is formed in the retainer extending from the pressuremember at an angle to the friction surface on the pressure member.

These and other features of the invention, as herein described andclaimed, will be apparent from the following detailed description takenin connection with the accompanying drawings, in which Fig. 1 is a viewin front elevation of a portion of a lock stitch shoe sole sewingmachine including a shuttle and a locking thread supply retainerembodying the features of the present invention;

Fig. 2'is a detail view in front elevation of the shuttle and retainer,including a raceway for the shuttle in the IIIIII of Fig. 2,illustrating the position of the thread pressure member shown in Fig. 3during withdrawal of thread.

The illustrated machine is a lock stitchshoe outsole sewing machinesimilar to that disclosed in the Gouldbourn et al. patent aboveidentified, having stitch-forming, and work supporting and feedingdevices including a curved hook needle 2, a needle looper. 4, a threadfinger 6, aloop spreader 8, acontinuously rotating shuttle 10, a worksupport 12, and a presser foot 14, all operating in a manner describedmore fully'in the patent. The shuttle is hollow and is formed in twoparts secured rigidly together and having between them a circular recessinto which is fitted a flanged raceway plate 16 secured rigidly to theframe of the machine. Instead of providing a locking thread supply caserotatably mounted within the shuttle,v

as in the patented machine, the illustrated machine is equipped with alocking thread supply retainer 18 removably mounted on the shuttle andarranged torotate with the shuttle in such a way that a modifying twistis impressed upon the thread extending from the retainer toward thework. Advantage is taken of. the modifying twist impressed upon thethread in the provision of a relatively hard' twisted threadarranged tobe partially untwisted by the rotation of the shuttle and the threadre-- tainer during operation of the machine. By so. doing the lockingthread is more readily formed into stitches and drawn more uniformly toa fixed depth within the work by the other stitch-forming devices, thethread. being rendered more flexible and of softer texture. by reasonof. the untwisting action.

The thread retainer 18 is formed with a central sleeve portion uponwhich is rotatably mounted a flanged bobbin 20 for carrying the supplyof locking thread. The sleeve portion of the retainer 18 has a centralbore of a diameter.

tolfit' a spindle 22 secured on the rear wall of the shuttle,

the; parts of the shuttle providing a cylindrical recess into which thebobbin is received and the retainer having at its forward end a radialflange portion forming a cover for the bobbin receiving recess of theshuttle. To insure that the supply retainerlS rotates uniformly with theshuttle a circumferential portion of the flange n the retainer is cutaway leaving a lip to fit beneath a plate 24 (see Fig. 2) secured to theshuttle. To enable the removal of the retainer from the shuttle theplate 24 has an integral pin 26 rotatably mounted on the shuttle and aspring-pressed ball 28 fits a depression on the under side of the plate.When the plate is rotated in a clockwise direction as viewed in Fig. 2,it clears the retainer for easy removal; otherwise, the locking threadsupply retainer has no further need for means of securement within theshuttle as by a separate swinging plate engaging its outer exposed face,as in the machine of the prior patent. However, such a plate isillustrated at 29 in Fig. l, but this plate is used only to control themovements of the needle thread.

To prevent overrunning of the bobbin 20 and any possibility of themodifying twist imparted to the locking thread between the shuttle andthe work from working its way back into the retainer recess within theshuttle in a manner to entangle or otherwise disturb the free withdrawalof thread, theillustrated shuttle is equipped with a novel pressuremember 30 engaging directly with a portion of the thread, which pressuremember is mounted yieldingly on the thread supply retainer to force thethread laterally into live frictional contact with the bobbin.

The pressure member 30 has a flat friction surface 32 formed at its freeend, and an angular thread guide arm 34 rotatable for free swingingmovement relatively to and independently of the retainer on a pin 36,supported in an arcuate wall of the locking thread supply retainer 18,the arcuate wall portion of the retainer being slotted to receive thepressure member 30 and the free end of the pressure member extendingalong an outer flange of the bobbin towards its center of rotation.

The locking thread contained on the bobbin is indicated at 38 and isunwound from the bobbin by intermittent pull on the thread extendingfrom the thread retainer, which pull is exerted by each needle loop asit is drawn into the work to set each stitch. Inherently the motion ofthread withdrawal is intermittent and at high speed, producing a strongrotational tendency for the bobbin to overrun and unwind thread withinthe recess in the shuttle for the thread retainer. For this reason thereis danger that the locking thread will become entangled and broken.

The locking thread as it leaves the bobbin 20 extends radially outwardlyfrom its hub into an open slot 40 entering the outer surface of the arm34 close to the pin 36 and extending about the angle of the arm toward aposition in front of the bobbin 20. The depth of the slot is so chosenthat the locking thread will not be engaged by any other part along theslot and will be withdrawn freely. After passing the angle in the arm ofthe pressure member 30, the slot 40 terminates and the thread is guidedby an angular groove 42 from the front of the arm rearwarclly beneathit, so that a portion of the thread is carried between the surface 32 ofthe arm and the bobbin flange. Along the friction surface 32 of the armis a shallow trough cut less deeply than the groove 42 in order to holdthe thread in position along the surface while exposing a substantialproportion of the thread thickness. In this way the movement of thesurface 32 toward the outermost bobbin flange presses the thread firmlyagainst the flange of the bobbin, which is formed with a flat surface 44to apply a fixed thread tensioning force to the locking thread. In sodoing, the surface 44 of the bobbin flange meets with substantialfrictional resistance for braking its rotation and the thread, as it iswithdrawn from the bobbin, supplies a constantly renewed freshfrictional wearing surface. The pressure of the thread against the outerbobbin flange acts not only directly to retard rotation of the bobbin,but it also presses the bobbin rearwardly along the sleeve portion ofthe retainer 18 and against a rearward wall of the shuttle, the rearwardwall being machined to fit closely with the rearward flange of thebobbin. Thus, the force of the pressure member has two frictionaleffects on the bobbin, one along the surface 44 of its forward flange,and the other along the rearward surface of its rearward flange.

To cause a fixed tensioning force to be applied yieldingly by thepressure member 30 to the portion of locking thread, the portion of thearm 34 comprising the pressure member between the pin 36 and the anglein the arm is engaged by an arcuate resilient leaf spring 46, secured toan arcuate portion of the retainer by a screw 48 passing through thespring into the container, the spring 46 being disposed between theretainer and the arm 34. To adjust the force of the spring 46 itscentral portion is perforated to receive a screw 50 also threaded intothe arcuate portion of the retainer and capable of being clamped inadjusted position by a locking screw 52.

For convenience in thread withdrawal from the locking thread supply andto overcome the irregular effects of static friction, the locking threadis withdrawn from the thread retainer in a direction axially of thebobbin through a guide consisting of an eye 54 formed concentrically tothe axis of shuttle rotation. Between the eye 54 and the frictionsurface 32 on the pressure member the locking thread extends through anangle to the friction surface 32 in a direction to counteract theyielding force of the spring 46 in accordance with the thread tension.Thus, the pressure of the member is quickly reduced when the threadstarts to be withdrawn from the bobbin, offsetting any tendency to clingto the surface 44 of the bobbin flange and the tension is controlledmore nearly dynamically rather than statically.

To guide the thread between the pressure member 30 and the axial eye 54it passes through an inclined passageway 56 just before it leaves theend of the pressure member. Under static conditions when a demand forlocking thread arises the angle in the thread as it enters the guide 56causes the pressure member to swing about the pin 36 through an angle 58(see Fig. 4) quickly reducing the pressure on the thread and avoidingirregular or excessive frictional resistance while maintaining a uniformdynamic frictional force thereon. As soon as the demand for lockingthread ceases, the tension in the thread drops abruptly causing thethread to be pressed with substantially the force of the spring 46against the flanged surface 44 of the bobbin, stopping its rotation andpreventing overrunning. Because of the fact that the surface 44 of thebobbin flange is flat the locking thread as it passes between thepressure member of the surface 44 also is flattened slightly on one sideand kept from twisting and displacement beneath the friction surface 32of the arm 34. By keeping the thread from twisting beneath the pressuremember 30 any modifying twist impressed on the thread by the rotation ofthe shuttle is kept fiom working its way back into the space occupied bythe bobbin and between its flanges where loose thread or accumulationsmight possibly be entangled. In this way the danger of threadentanglement is substantially reduced and maximum uniformity in threadwithdrawal is insured.

The nature and scope of the invention having been indicated and aparticular embodiment having been described, what is claimed is:

1. A sewing machine locking thread supply retainer containing a bobbinon which a supply of locking thread is wound, having in combinationtherewith means to prevent overrunning of the bobbin comprising a threadengaging member pivoted to the thread retainer and formed with afriction surface for pressing the thread against the bobbin.

2. A sewing machine locking thread supply retainer containing a bobbinon which a supply of locking thread is wound, having in combinationtherewith means to prevent overrunning of the bobbin comprising a threadengaging arm pivoted to the thread retainer for movement toward and fromthe bobbin and formed with a friction surface for pressing the threadagainst the bobbin, a yielding member on the supply retainer acting onthe arm to apply a fixed thread tensioning force to the thread runningbetween the arm to the bobbin and a guide for the thread extending fromthe arm at an angle to the friction surface thereon, to counteract theforce of the yielding member as the thread is withdrawn from the'bobbin.

3. A rotary shuttle for a sewing machine having a locking thread supplyretainer in the shuttle containing a flanged bobbin between the flangesof which a supply of locking thread is wound, in combination with meansto prevent overrunning of the bobbin comprising a thread engaging armpivoted on the thread supply retainer for movement toward and from thebobbin and formed with a friction surface between which and one flangeof the bobbin the thread is pressed, a yielding member on the threadcase acting on the arm to exert a fixed thread tensioning force on thethread running between the arm and said bobbin flange in a direction topress the other flange of the bobbin against the thread case and a guideformed concentric to the axis of shuttle rotation for the threadextending from between the arm and the firstrnentioned bobbin flange ina direction to counteract the force of the yielding member as the threadis withdrawn from the outlet.

4. A lock stitch shoe sewing machine, having a hook,

needle, a continuously rotating shuttle including a lock.- ingthread'case rotating with the shuttle and containing a bobbin on which asupply of locking thread is wound and other stitch-forming devices forcarrying loops of thread from the needle to the shuttle and forretracting each needle loop from the shuttle to draw the locking threadsurrounded by each loop into the work, the direction of rotation of theshuttle causing the locking thread 6 i i running between the bobbin caseand the work to be untwisted, in combination with means to preventoverrunning of the bobbin conrtprising a thread engagaing member on thethread case for pressing the thread against the bobbin frictionally, anda guide for the thread disposed at an angle to that portion of thethread pressed between pressure member and the bobbin to counteract thepressure of the said member on the thread as the thread is withdrawnfrom the guide.

5. A sewing machine locking thread supply retainer containing arelatively rotatable flanged bobbin from which a supply of lockingthread is unwound intermittently, producing a strong rotational tendencyfor the bobbin to overrun, said retainer having in combination therewithmeans to prevent overrunning of the bobbin in the retainer as the threadis withdrawn, comprising a thread-engaging arm, means for mounting thethreadengaging arm on the thread supply retainer for free movementrelatively to and independently of the retainer and the bobbin, betweenwhich thread-engaging arm and a flange of the bobbin the thread isdirectly pressed frictionally, and resilient means disposed between thethread supply retainer and the arm for actuating the arm to apply atensioning force yieldingly to the portion of the thread running betweenthe thread-engaging arm and the bobbin flange.

References Cited in the file of this patent UNITED STATES PATENTS

